Late Permian kuroko-type mineralization in the Bully Hill area of the East Shasta district formed along two horizons within the Bully Hill rhyolite. In the Bully Hill, Rising Star, and Copper city mine areas, syngenetic mineralization is underlain by alteration zones characterized by addition of SiO₂ and K₂O, loss of NaCO, CaO, and Fe₂O₃* , and the assemblage quartz + sericite + pyrite. Quartz precipitation in the upper portion of the zones led to cyclic sealing of fluid flow, rupturing of the seal, quartz supers aturation, focused fluid discharge, and formation of sulfide mounds on the seafloor. Syngenetic mineralization occurred in several stages: (1) deposition of fine-grained banded sulfides and gangue; (2a) recrystallization of Stage 1 minerals, and void-filling by pyrite + weakly chalcopyrite-diseased sphalerite ± barite; (2b) deposition of coarsely-crystalline pyrite + heavily chalcopyrite-diseased sphalerite; (3a) void-filling and replacement by galena + chalcopyrite + tetrahedrite-tennantite; (3b) replacement by chalcopyrite; and (4) replacement by barite. ΣSO₄⁼ and H₂S contents of hydrothermal fluids decreased from Stages 2a to 3a. δ³⁴S values of sulfides increased successively from Stages 1 (-15.8 per mil) to 3a (3.0 per mil), reflecting variable inputs of biogenic sulfur and deep-seated fluid evolution. δ³⁴S values of syngenetic barites range from 12.4 to 22.5 per mil, reflecting cold seawater and hydrothermal sulfur sources, respectively. δ³⁴S values of epigenetic pyrite and barite within the alteration zones range from -0.7 to 2.7 per mil and 12.4 to 24.1 per mil, respectively. Primary and pseudosecondary fluid inclusions in epigenetic minerals have filling temperatures of 240 to 260 °C and salinities of 3 to 12.3 equivalent weight percent NaCl. Lower limits of fluid salinities and δ³⁴S values of barite indicate that seawater was a primary component of the hydrothermal fluid, and that seawater also mixed with discharging fluids on the seafloor. High fluid salinities, the lack of a silica source, and the close link of magmatism with mineralization indicate that magmatic fluids may have been an important component of the hydrothermal fluids.

Different patterns of uniform-uplift periods associated with passage of the Mendocino triple junction (MTJ) and a change in tectonic regime are based on altudinal spacing analyses of nine flights of marine terraces. Rates of uplift appear to increase from <1 m/ka to 4-5 m/ka, with periods of most rapid uplift that are progressively younger toward the triple junction. The MTJ was about 55 km to the south at about 1 ma ago, where uplift has been uniform at about 1.3 m/ka during the last 300 ka. Maximum uplift of about 4 m/ka is occurring 20-40 km south of the MTJ; prior to about 100-150 ka uplift was slow, being only 0.2-0.5 m/ka. Ten km to the north of the MTJ, accelerated uplift has occurred only during the last 60 ka. Relative strength of soil development in sandy marine deposits on five Pleistocene and Holocene (1.7 to 120 ka) marine terraces near the MTJ is one basis for relative age estimates and correlation of terrace soils. Organic carbon content in the upper 70 cm of the soil profile increases exponentially, and pH decreases exponentially; for both properties steady state is attained by 40 ka. Whole profile content of clay, total free iron oxyhydroxides (Fe(d)), and total free and para-crystalline aluminum oxyhydroxides increase nearly linearly until at least 120 ka. Comparison of these soils with four marine terrace soils (103-405 ka) 100-120 km to the south indicates that maximum percent values of clay and Fe(d) increase exponentially, with highest values reached at about 120 ka. Analysis of three-dimensional morphological properties of 25 coastal drainage basins that have evolved in areas of low (<1 m/ka), intermediate (1-3 m/ka), and high (>3 m/ka) rates of uplift near the MTJ identified channel slopes as the best indicator of tectonism in the landscape. Lower order tributaries reflect tectonically-controlled differences best. The largest streams examined, of third order, are able to adjust to most base-level change and maintain their profile form, whereas lower order streams farther upstream tend to accumulate the effects of net base-level fall, and have steepest profiles in the areas of highest uplift. Although first order streams are excellent indicators of highest uplift rate areas and regional differential tilting, they are less useful in distinguishing between low and intermediate uplift rate areas. Analysis of the longitudinal profile of the main trunk stream of 10 of the 25 drainage basins with the stream-gradient index (Hack, 1957) was useful to broadly categorize uplift rates, and to distinguish between low and intermediate uplift rate streams.

No description available.

The problem of determining the response of tree ring width growth to monthly climate is examined in this study. The objective is to document which of the available regression methods are best suited to deciphering the complex link between tree growth variation and climate. Tree-ring response function analysis is used to determine which instrumental climatic variables are best associated with tree-ring width variability. Ideally such a determination would be accomplished, or verified, through detailed physiological monitoring of trees in their natural environment. A statistical approach is required because such biological studies on mature trees are currently too time consuming to perform. The use of lagged climatic data to duplicate a biological, rather than a calendar, year has resulted in an increase in the degree of intercorrelation (multicollinearity) of the independent climate variables. The presence of multicollinearity can greatly affect the sign and magnitude of estimated regression coefficients. Using series of known response, the effectiveness of five different regression methods were objectively assessed in this study. The results from each of the 2000 regressions were compared to the known regression weights and a measure of relative efficiency computed. The results indicate that ridge regression analysis is, on average, four times more efficient (average relative efficiency of 4.57) than unbiased multiple linear regression at producing good coefficient estimates. The results from principal components regression are slight improvements over those from multiple linear regression with an average relative efficiency of 1.45.

No description available.

Plant indicator species and longitudinal paleobotanical data were used as independent measures to document the human ecological record of the contact period in southern Marin County, California. These data suggest that archaeological and documentary records are insufficient for examining changes in land management and use during the contact period. Prior to A.D. 1579, Western Miwok peoples had not encountered Europeans face to face. This early phase of the contact period is marked the possible introduction of New World species through passive cultural vectors. Two brief encounters occurred between the Miwok and Europeans between A.D. 1579 and 1775. Introduced and weedy plant species from fossil samples appear to confirm these encuentros and confirm the archeological evidence for intermittent contact during the second phase of the contact period. Modern and fossil pollen samples suggest that the intensity of human disturbance is geographically stratified and related to exploration, procurement, and management of specific resources. Coastal prairie, the redwood forest, and Bay salt marshes were the most affected by the second phase of the contact period. Shifts in vegetation diversity and increases in the numbers of introduced and weedy species were compared between ruderal and undisturbed contexts. These data were used as analogs to monitor the final phase of contact between A.D. 1775 to 1817. Hypotheses derived from ethnohistoric and ethnographic sources that suggest rapid shifts in land management practices and changes in plant representation were corroborated by some pollen data. Specifically, the ecological responses to the suppression of anthropogenic burning, changes in land tenure and parcelization, and the initiation of grazing and logging practices were examined. The cumulative impacts of introduced plants, shifts in land management from Miwok to Euroamerican-dominated resource procurement and subsistence practices, and ecological responses of plant species suggests that the contact period might better be defined on ecological terms rather than by purely material cultural or ethnographic definitions. In southern Marin, paleobotanical data provide a measurable indication of the ecological character of the pre-contact landscape and the cultural processes that effectively altered its character during the contact period.

A collection of short fiction set in and around Southern California.

Spanish authorities used two agencies to occupy and control California as a royal province from 1769 to 1821: the church and the army. While the story of the missions and the missionaries has been thoroughly chronicled, little attention has been focused on the men who comprised Spain's military forces. This thesis examines the experience of the royal soldier in California to determine his significance in the Golden State's Spanish colonial era. The journals, diaries, and correspondence of the soldiers, missionaries, explorers, traders, and foreign rivals who visited or occupied the province comprise a major part' of the source material. The variety of viewpoints represented by these · documents facilitated examination from several perspectives. Another valuable primary source was the Spanish frontier regulations, which provided the royal perspective on the military enterprise. Published materials based on documents in the major archival repositories such as those in Mexico, Spain, and the Bancroft Library in California were accessible through works in the Portland State University Library and the Oregon Historical Society which supplied sources pertinent to this investigation. Secondary works by historians provided both a historical background and data on specific aspects of a soldier's life. Cited periodical articles concentrated more specifically on the military experience both in California and the Spanish northern frontier.

Graduation date: 2005

Anomaly timescales for the last 90 million years, derived from marine magnetic profiles and published prior to mid-1979, are summarized, illustrated for comparison, and critically reviewed. A revised timescale is constructed using calibration points which fix the ages of anomalies 2.3', 5.5, 24, and 29. An equation is presented for converting K-Ar dates that is consistent with the recent adoption of new decay and abundance constants. The calibration points used in the revised timescale, named NLC-80, are so converted, as are the boundary ages of geologic epochs within the range of the timescale. NLC-80 is then used, along with recently acquired and rigorously navigated underway geophysical data from the region of the mouth of the Gulf of California, to prepare detailed bathymetric, gravimetric, and seismo-tectonic maps of the area. The basement ages at DSDP Leg 63 drilling sites 471, 472, and 473 are estimated from magnetic anomalies fit to timescale NLC-80. The estimates agree with biostratigraphically determined basement ages and support the proposal that an aborted ridge of about 14 MY age has left a small fragment of the Farallon Plate beneath the Magdalena Fan. Several large inactive faults are identified on the deep-sea floor west of the tip of the peninsula of Baja California. Additional magnetic anomaly profiles and bathymetric profiles across the Rivera Ridge are interpreted. These contradict the existence of a 3.5 MY old aborted spreading center on the Maria Magdalena Rise. Instead, it is proposed that an episode of subduction of the Pacific Plate beneath the southeastern tip of Baja California, concomitant with strike-slip faulting west of the peninsula, occurred and that this subduction may be responsible for the uncentered location of the Rivera Ridge within the mouth of the Gulf of California. A single magnetic anomaly profile obtained northeast of the Tamayo Fracture Zone is used to determine that the rate of Pacific/North American plate motion, for the last 3 MY is 68 km/MY at this location. This result, if correct, indicates that the peninsula of Baja California is separating from mainland Mexico faster than the Rivera Ridge is generating oceanic crust in the wake of opening in the gulf. This, in turn, requires that either slow diffuse extension is occurring presently across the Maria Magdalena Rise, or across the Cabo Corrientes-Colima region, or that the portion of North America south of the trans-Mexican volcanic belt is moving right-slip with respect to the North American Plate at a rate of 10-20 km/MY. Large horsts and many smaller continental fragments are found within the southern gulf. Several of them have active seismic boundaries, while others have apparently foundered. The gulf began to open approximately 14-15 MY ago with slow, diffuse block-faulting and the deposition of the Maria Magdalena Fan at the mouth of the gulf. Oceanic crust was exposed in the gulf by about 9-10 MY, at the same time that the Rivera Ridge began reorienting by clockwise rotation. Strike-slip motion along the Tosco-Abreojos Fault took up some of the Pacific/North American motion with the remainder occurring within the gulf itself. During this period the Pacific Plate forming within the gulf was slowly subducting beneath Baja California. By 4-5 MY subduction ceased and all of the Pacific/North American plate motion was shifted to the Gulf of California fault system. The gulf and peninsula of California are still in the process of adjusting to the change from Pacific/Farallon to Pacific/North American motion. / Graduation date: 1982